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By J. E. Willson, N. K. Bohidar

An evaluation of internal stress distribution based on photoelastic studies and destructive testing of simulation models shows that pillar failure is a function of the internal stress distribution, and that stability can be changed by altering the internal stress pattern. Induced stresses in three-dimensional epoxy disks subjected to uniaxial forces were evaluated by photoelastic studies. Stress profiles across different sections perpendicular to the loading direction revealed two maxima for each profile. Based on the stress distribution for the entire column, an attempt was made to explain pillar spalling and the hour glass pattern of failure in a mine pillar. For maximum stability and optimum design of mine pillars, it is necessary to consider the external forces, the nature and distribution of induced stresses and the characteristics of the pillar material as determined in the laboratory. This paper summarizes the research done by N. K. Bohidarl and Ben L. seegrniller2 as partial fulfilment of the requirement for Master of Science degree in Mining Engineering, University of Utah. It is an evaluation of a study to determine the stress distribution in short columns in order that regions of high stress concentration in mine pillars may be found and their effect on pillar failure be ascertained. The ratios of the dimensions of the columns studied are representative of those found in mines located in flat-bedded deposits. The weight of the overburden generally constitutes the major external force. This force is calculated by taking into account specific weight and thickness of the cover. Determination of the distribution of this force on pillars may often require a complex analytical study. There have been many investigations of the strength

Jan 1, 1968

By J. R. Hunter

Current trends in mining practices within the United Kingdom, with particular reference to longwall retreating systems in thick and steeply pitched coal seams at depth, are explained. Various successful mining layouts are considered with their associated machinery and operation, together with the future trends in mining practices to obtain higher outputs. Environmental difficulties are tabled and discussed, including strata control, methane emmision, and dust prevention, together with some modified systems and techniques to overcome them. The problems associated with developing and maintaining a continuance of longwall panels are outlined. The constraints on technical designs and output achievement imposed by noncommercial factors are also considered.

Jan 1, 1978

By C. G. Dunn, M. Sharp

HE orientations of 137 crystals of copper pro-T duced by secondary recrystallization in a cube texture matrix have recently been obtained. Although the crystals were not prepared for the purpose of determining a secondary recrystallization texture, the orientations obtained proved to be rather interesting, as they confirmed, in part, published results and also disclosed additional preferred orientations in the texture. The investigation of Dahl and Pawlek,&apos; Bowles and Boas,&apos; and Kronberg and Wilson3 showed respectively that the orientations of secondary grains growing in a cube texture matrix were related to those of the primary grains by a rotation of approximately 30" about [001], the rolling direction, by 30" about a <111> direction, and by either 22" or 38" about a <111> direction. Kronberg and Wilson also obtained a component of the texture similar to that of Dahl and Pawlek except the angle of rotation about [001] was 19". When the cube texture matrix was deformed a small amount, Kronberg and Wilson also obtained large grains on subsequent annealing corresponding to a rotation of 15" about the normal to the sheet, but these grains should not be classified as secondary recrystallization grains since they were produced subsequent to mechanical straining. The particular texture obtained, of course, depends on the composition of the copper and the processing schedule employed, since these factors markedly affect the primary recrystallization texture and the sharpness of any cube texture produced. In the present investigation, pieces of OFHC copper in the form of M in. round bars were cold forged to a thickness of about 0.40 in., annealed 1 hr at 350°C in an atmosphere of hydrogen, and cold rolled crosswise to a thickness of 0.200 in. These pieces were given a penultimate anneal of 1 hr at 350°C in hydrogen and a 90 pct cold-rolling reduction lengthwise to a thickness of 0.020 in. Indentations generally were put in one end of the as-cold-rolled strips to promote earlier formation of secondary grains.

Jan 1, 1953

By J. R. Sturgul, J. C. Wynn

Computers and computer applications in geophysics are fairly recent innovations. The area of data handling is one that has found many immediate applications. Initially, the use of computers involved in almost all cases, a batch-input arrangement requiring a trip to the local computer center, a wait and another trip. Even though the computer worked at incredible speeds, the time-delays, in case an error in the input data developed, often could be several days. Use of computers in mining exploration by medium-sized or small-sized companies and contractors has been almost non-existent beyond simple data reduction work. The principle J. R. Sturgul, SME member, and J. C. Wynn, both affiliated with the Dept. of Geosciences, University of Arizona, Tucson, presented this paper at the Eleventh International Symposium on Computer Applications in the Minerals Industry, reasons appear to be the time factor and the inconvenience of the frequent trips involved. With the advent of time sharing systems, whereby a company need only have access to a terminal, the main objections can be overcome. An Apparent Solution An apparent solution to the time and distance inconveniences which would permit more extensive use of computers in geophysical exploration, is to buy or lease/purchase a medium-sized computer and install it in or near one&apos;s office. This is a formidable proposition in terms of cost and programming time on both respects, but several mining companies of larger size have already gone this route. In most cases, the computers have been expensive devices with a limited memory or core size. For routine data handling this memory size is not restrictive; however, for many geophysical applications such as three-dimensional modeling this can be critical.

Jan 10, 1973

By Alexander Bowie

Of the following problems, some have been suggested by recent articles in technical journals, which have led me to believe that the mathematical discussion here submitted may be of use to mining engineers. Problem I. To Find the Grade or Angle of Inclination upon which the Power Required to Move a Loaded Car Down-hill Will Haul an Empty One Up-hill. Let a be the desired angle of inclination; C, the coefficient of&apos; friction; W and w, the weight in pounds of the loaded and of the empty car, respectively.

Jan 1, 1902

By Ripu Daman Lama

The size of coal pillars in mines until recently has been determined by experience without being based upon scientific investigations. As a consequence, the size of pillars had invariably been larger than could be accounted for because of the number of unknown factors involved which influence the strength, dictating the use of large safety factors. With the mining going deeper, the size of the pillars greatly increases and sometimes a considerable portion of the mineral property are blocked in the mine pillars required to support the superincumbent strata. With the advances in the field of Rock Mechanics, attention of mine planning engineers has been focused upon the design of mine pillars for safe and efficient working as well as decrease losses of coal. The problem involves the study of three factors: (1) Presence of stresses in the area and their distribution on pillars in the course of extraction. (2) The influence of external factors on the strength of coal. (3) The inherent mechanical properties of coal. These aspects have been studied by a large number of investigators, the first by in-situ stress measurements and photoelastic studies and the second and third aspect by studies conducted in the laboratory on small size specimens (Bunting, 1911; Evens & Pomeroy, 1961; Gaddy, 1956; Greenland et al, 1941; Steart 1954). The size of the specimens tested in the laboratory has been limited to a few inches and the results obtained have been extrapolated by large factors, sometimes several hundred times the largest specimen tested. In these tests much consideration has not been given to

Jan 1, 1971

By Jan M. Mutmansky, Y. J. Wang

Mine ventilation analysis is an engineering discipline that can be considered a branch of the body of science known as network analysis. Likewise, the group of engineering procedures known as the critical- path method (CPM) is considered a branch of network analysis. It is therefore not surprising that mine ventilation network analysis and CPM have many similarities. These similarities are useful in analyzing several types of mine ventilation problems and will be utilized in this paper. The analogy between the free split in a ventilation circuit and the critical path in a scheduling network has been recognized by Owili-Eger (1973). While this was recognized as a property of a general ventilation network, many important applications to controlled- splitting problems also exist. The mathematical procedures necessary to apply CPM and network methods have previously been presented (Wang, 1981; Wang, 1982). This paper will illustrate the implementation of these methods by application to mine ventilation networks.

Jan 1, 1982

By N. B. Aughenbaugh, W. C. Patrick

The availability of a thorough, simple-to-use roof fall classification system is desirable for several reasons. First, such a system would expedite the reporting of falls for the purposes of estimating material removal costs, analyzing damage levels, and complying with federal regulations to report falls in certain areas of the mine. Second, the classification system would allow the mining engineer to record falls routinely with little time and effort expended. This would encourage him to make observations concerning what type of roof support would work best in a given situation. Third, and probably most important, an

Jan 3, 1979

By C. W. Spencer, R. A. Rummel, F. N. Rhines

SPECIMENS of five cast Cu-Bi alloys, containing 4.68, 0.53, 0.043, 0.0064, and 0.0025 wt pct Bi and cast pure copper were subjected to a bend test to determine their relative ductility. Using metallo-graphlc methods the structures of the fractured surfaces were compared with those of the polished cross sections. Embrittlement was found to be associated with the presence of a second phase in the grain boundaries although, in the lower bismuth

Jan 1, 1958

By John F. Havard, Armine F. Banfield

Sooner or later, we all get involved in the economic study and valuation of a mineral deposit. To communicate clearly the necessary information, we must scrupulously use various terms with specific meaning. All these terms-such as ore, exploration, development, production, reserves, proven ore, probable ore, possible reserves, resources, as well as similar terms applying to coal-are continually on the lips of anyone who reports on the economic aspects of a mineral deposit at the exploration, development, and production stages. The meaning of these terms is even more important in feasibility studies to determine whether a deposit should be put into production. Finally, careless use of these terms in reports published for public financing may, and sometimes does, lead to prosecution of the writer for misleading information.

Jan 7, 1975

Welfare endeavor in connection with both the metal and the coal mines of Utah has shown gratifying progress during recent years and both the operators and their employees are deserving of much credit for the efforts put forth to better living, working, educational and receational conditions in most of the mining camps of the state. In the older metal mining camps of Utah, where the towns are incorporated and independent of the mining properties operating in the vicinity, less opportunity is presented for the companies to exercise efforts looking towards improved welfare conditions than is the case of camps located on company ground and under the full control of operators.

Jan 1, 1925

By C. E. Abbott

THE Birmingham district, Alabama, is distinctive in the proximity to one another of its deposits of iron ore, coal and flux. These three basic requisites for the making of iron and steel are found within a radius of 10 miles. Both dolomite and limestone are produced, the former for blast-furnace flux and the latter for basic open-hearth operations. The Tennessee Coal, Iron and Railroad Co., a subsidiary of the United States Steel Corporation, operates a limestone mine at Muscoda, near Bessemer, 12 miles southwest of Birmingham, served by its own railroad transportation system. The mine has a capacity of 130 tons per hour. Average analyses of a recent month&apos;s production are as follows: Fe2O3 Si02 A12O3 CAC03 MGCO Lump, per cent 0.51 0.22 98.63 0.14 Crushed and washed, percent 0.70 0.26 98.36 0.18 Lump stone, 2 1/2 to 7 1/2 in., is used in open-hearth operations at Fairfield Steel Works. Fine crushed and washed stone, 1 ¼ to 0.063 in., is calcined at the, lime-burning plant and used for lime charges at the Ensley open hearths.

Jan 1, 1936

By Robert N. Eli

The application of Geographic Information System (GIS) technology to support the planning, design and analysis of coal mines is discussed. Traditional two-dimensional GIS structures are modified to produce a three- dimensional GIS system that combines the efficient topologic description of a cubic grid cell skeletal structure with the precision surface representation of a Triangulated Irregular Network (TIN). The surface terrain and any subsurface strata, such as a coal seam, are represented by separate TIN&apos;S. Any attribute data to be assigned to the TIN&apos;S are stored in polygon overlays. Any remaining spatial data are stored as link strings or nodes in a global data set. The most valuable application of the system is the production of map products. Both projections and cross-sections of surface or subsurface structures are possible, in either horizontal or vertical planes. Engineering data, including lengths, areas, or volumes, can be calculated.

Jan 1, 1983

By John Griffen

OF the western European countries, only England has made any extensive use of equipment developed initially by the coal preparation industry of the United States. About 20 years ago, the Chance sand flotation process for cleaning coal was introduced in England, and it has had a fairly wide adoption, particularly in the South Wales coal fields. In recent years, particularly since 1946, a considerable number of Denver flotation cells have been installed throughout the English coal fields for the cleaning of slurry. Until the advent of the Denver cells, the flotation of coal slurries in Western Europe had been done largely with the Mineral Separations cell or its modifications. Kleinbentik of Dutch State Mines had developed a cylindrical cell used in Holland and occasionally in Belgium and France. In England, the establishment of the National Coal Board to control the planning and operation of all coal production has retarded somewhat modernization of properties. A considerable period of study was required before definite long-range plans could be formulated. It was soon recognized that stopgap measures were needed in many cases to bridge the period until final plans could be developed and consummated. One of the stopgap problems in coal preparation was providing plants of small and medium capacity that could be used for a few years at one site and yet could be moved economically to another site so as to reduce depreciation charges per year and per ton. Such plants are being installed but the most satisfactory answer probably has not yet been found. One such installation uses a Norton Baum jig to wash 6 in. to 0. The equipment is in a steel structure rather than in a reinforced concrete frame with brick curtain walls, which is the normal structure for permanent plants. Since England has between 700 and 800 preparation plants for an output of 200 million tons per year, one of the long-range objectives is a consolidation of mine output which will require fewer coal

Jan 1, 1952

By Wilford Stork

CERTAIN influences of oxygen on iron have been known for many years and it has always been considered one of the worst enemies of the iron and steel founders. Nobody had a good word for it, hence little was done to make use of this oxygen. In all the fields of foundry practice, the desideratum was "melt without oxidation of the metal." In the consideration of the influence of oxygen on cast iron, we must not confuse this condition with oxidized iron caused by poor melting conditions, due to a high bed, heavy charges, low coke ratio, excessive melting rate, high blast, or poor charging. It is admitted that oxygen absorbed by iron melted under these conditions has a deleterious effect on the properties of the iron. The writer has had experience both in the melting under such poor conditions and in remedying these bad conditions and considers the product far inferior to iron melted under normal conditions. As stated by Dr. Richard Moldenke,1 such iron has a higher melting point and high combined carbon, is sluggish, and contains slags and oxides in solution in the liquid, causing slag inclusions and gas occlusions, thus producing defective castings. This oxidized condition cannot be counteracted or removed by any of the known deoxidizers; it can be remedied only by proper melting conditions. Such iron is really burned, whereas the iron considered in this paper was melted under normal conditions with moderate blast, correct bed height, light charges of iron, and low coke consumption and is not in this category at all. In 1914, the late J. E. Johnson, Jr., startled the metallurgists of the world when he published his results on the advantages of oxygen on cast iron.2 His work is so convincing and so logical, in spite of the common and well-established notions on the subject, that nobody has been able to refute a single argument. Such an eminent authority on iron and steel metallurgy as Prof. H. M. Howe has accepted the work in all its details in his latest book3 The work of J. E. Johnson, Jr., has revolutionized

Jan 6, 1919

By K. A. Grace

Reserves are the basic foundation of any mining enterprise, but a lack of understanding of the concept of resources and reserves is still a frequent cause of failure in mining ventures. A review of the development of the resource-reserve concept emphasizes the necessity for a common language, and the classification system as set out by the US Geological Survey and Bureau of Mines is advocated as the basis for this. Because of its strong economic connotation, the term reserves should be severely restricted in its use, and should encompass mining and processing factors. Modifications to the basic definition of reserves to accomplish this are proposed. Caution must be used in the quantification of undiscovered or hypothetical resources, particularly in juxtaposition with known resources data.

Jan 1, 1985

By William E. Bonini, Eugene A. Hickok

IN the course of an investigation directed toward expanding ground-water facilities in Essex and Morris counties, New Jersey, the Board of Water Commissioners of the city of East Orange authorized a seismic-refraction survey1 for the purpose of delineating bedrock topography below unconsolidated overburden. Results of the survey were highly satisfactory and led to the preparation of a comparatively detailed bedrock contour map. Knowledge of the bedrock depth and configuration was an important aid in selection of sites for test drilling. The portion of the East Orange Water Reserve under consideration is in the flood plain of the Passaic River about 10 miles west of Newark, N. J. The flood plain is about 175 ft above mean sea level and is bordered by low hills rising to elevations of approximately 250 ft. The bedrock underlying the Water Reserve consists of sandstone and shale of the Triassic Brunswick formation and is covered everywhere by deposits of unconsolidated glacial outwash sand and gravel, lacustrine clay, and recent river silt as much as 150 ft thick. Yield of wells in the sandstone and shale averages 100 to 200 gpm. Since production wells constructed in the sand and gravel aquifer in the buried river valley shown on the contour map (Fig. 1) yield 300 to 1400 gpm, it was proposed to locate additional production wells in this buried valley, where the yields per well would be maximum.

Jan 4, 1958

By M. E. Tyrrell, Alan H. Goode

The application of a simple, two-dimensional computer technique for evaluating rock burst potential in cut-and-fill stopes was investigated. The principal purpose of the study was to compare the effectiveness of high-modulus fill and destressing as aids in the control of rock bursts. Two conclusions that are probably of general applicability are drawn. First, high-modulus fill is ineffective as a means of increasing the mine stiffness and acts to control rock bursts only if it supports enough load to reduce substantially the stresses on the unmined vein material. Second, destressing is most effective if it is performed when the vein material is near the point of failure.

Jan 1, 1975

By Zay Jeffries

Discussion of the paper of ZAY JEFFRIES, A. H. KLINE and E. B. ZIMMER, presented at the New York meeting, February, 1916, and printed in Bulletin No. 108, December, 1915, pp. 2359 to 2369. ZAY JEFFRIES, Cleveland, Ohio.-The original portion of this paper represents a laboratory method for determining grain size in metals. It was developed not so much to find a quick method as it was to facilitate certain work which I was carrying on a couple of years ago. I had a great many determinations to make and the planimeter method was very slow, as was the Heyn method, and both of them were laborious, so I tried to shorten the time of the determinations. Since preparing the present paper, Dr. T. M. Focke, Professor of Mathematics at Case School of Applied Science has called my attention to the fact that both the Heyn and Intercept methods are mathematically

Jan 5, 1916

By Joseph A. Gill, Ernest A. Curth

The Government and Leeco concluded a cost-sharing agreement in 1976 to demonstrate longwall mining of a thin coalbed, 1 m or less, in a mine near Hyden, Ky. A premining investigation laid the groundwork for mine design and equipment specifications. Four- legged shields, a face conveyor, a stage loader and an in-web shearer were selected to operate on a 183 m face. Lengwall mining began in 1979 and initially was slowed by low mining height and equipment problems. A rock mechanics program provides early warning capability and criteria for future mine design. Monitoring of surface effects is included.

Jan 1, 1981